jparchitectus
29-08-2005, 17:35
The Bridge
In 1994 London Docklands Development Corporation held a design competition for a pedestrian bridge to link the new Canary Wharf commercial towers development with the refurbished Victorian warehouses of West India Quay It was a condition of the competition that no loads be imposed on the waterfront at the two ends
The Insect Water Skater
Future Systems with Anthony Hunt Associates won the design competition with a floating structure. This is a gently curved, 94m arc aluminium deck supported on four sets of splayed tubular steel legs which rest on largely-submerged pontoons secured by light-tension piles. The effect has been likened to that of an ‘insect water skater’. The ‘insect’ lies low on the water, avoiding visual competition with the buildings of Canary Wharf and West India Quay.
Bridge Structure
The bridge is a steel structure with 750x300 U - shaped spine beam. Tapered angles, set diagonally to the spine beam, help to cross-brace it. The splayed legs are in 244.5 CHS and are bolted to the spine beam. They terminate in solid, cone-shaped connections welded to circular plates that are bolted to the pontoons. Only 500mm of the 2800mm diameter foam-filled pontoons are above the water surface.
Fabrication and Erection
The use of pontoons allowed tie bridge to be workshop fabricated and floated upstream into position. It was fabricated in two sections by Littlehampton Welding and transported by road to Royal Albert Dock, where it was assembled and towed by tug through the Thames Barrier and into West India Dock. Here the pontoons were positioned and jacked down on to the piles.
Bridge Deck
The bridge deck is divided into three, two gently inclined sections on each side of a central section, 6.6m long, that can be lifted hydraulically to allow boats to pass through. The opening action is by a simple cantilever counterbalance. Two stainless steel pistons, operated by hydraulic cables set in the spine beam, are activated as necessary by the harbourmaster, from a console on the dockside. The deck is a 75mm deep aluminium box section with grooved pattern on the surface to give a non-slip surface. Its edges rest on perimeter supports comprising a steel T-section welded to a half-round 219.1CHS. These steel sections help stiffen the deck.
Pedestrian Balustrade
A balustrade of stainless steel cables protects pedestrians. Vertical, tapering steel flats on each side support a tubular stainless steel handrail, which curves round to become the end balusters. The cables are connected to these and are tensioned with turnbuckles.
Lighting
The bridge is lit at night by uplighters fitted with dichroic filters, which change perceptions of colour from different sightlines. These are inset into the aluminium deck at its edges, giving the effect of airport runway lights. Downlighters with translucent lenses are fixed underneath to shine on the water, supplemented by floodlights fixed to the bridge legs. Sealed polycarbonate units containing miniature fluorescent tubes are set inside the handrails to direct light on to the deck. The lighting is supplied by cables located in ducts below the deck.
In 1994 London Docklands Development Corporation held a design competition for a pedestrian bridge to link the new Canary Wharf commercial towers development with the refurbished Victorian warehouses of West India Quay It was a condition of the competition that no loads be imposed on the waterfront at the two ends
The Insect Water Skater
Future Systems with Anthony Hunt Associates won the design competition with a floating structure. This is a gently curved, 94m arc aluminium deck supported on four sets of splayed tubular steel legs which rest on largely-submerged pontoons secured by light-tension piles. The effect has been likened to that of an ‘insect water skater’. The ‘insect’ lies low on the water, avoiding visual competition with the buildings of Canary Wharf and West India Quay.
Bridge Structure
The bridge is a steel structure with 750x300 U - shaped spine beam. Tapered angles, set diagonally to the spine beam, help to cross-brace it. The splayed legs are in 244.5 CHS and are bolted to the spine beam. They terminate in solid, cone-shaped connections welded to circular plates that are bolted to the pontoons. Only 500mm of the 2800mm diameter foam-filled pontoons are above the water surface.
Fabrication and Erection
The use of pontoons allowed tie bridge to be workshop fabricated and floated upstream into position. It was fabricated in two sections by Littlehampton Welding and transported by road to Royal Albert Dock, where it was assembled and towed by tug through the Thames Barrier and into West India Dock. Here the pontoons were positioned and jacked down on to the piles.
Bridge Deck
The bridge deck is divided into three, two gently inclined sections on each side of a central section, 6.6m long, that can be lifted hydraulically to allow boats to pass through. The opening action is by a simple cantilever counterbalance. Two stainless steel pistons, operated by hydraulic cables set in the spine beam, are activated as necessary by the harbourmaster, from a console on the dockside. The deck is a 75mm deep aluminium box section with grooved pattern on the surface to give a non-slip surface. Its edges rest on perimeter supports comprising a steel T-section welded to a half-round 219.1CHS. These steel sections help stiffen the deck.
Pedestrian Balustrade
A balustrade of stainless steel cables protects pedestrians. Vertical, tapering steel flats on each side support a tubular stainless steel handrail, which curves round to become the end balusters. The cables are connected to these and are tensioned with turnbuckles.
Lighting
The bridge is lit at night by uplighters fitted with dichroic filters, which change perceptions of colour from different sightlines. These are inset into the aluminium deck at its edges, giving the effect of airport runway lights. Downlighters with translucent lenses are fixed underneath to shine on the water, supplemented by floodlights fixed to the bridge legs. Sealed polycarbonate units containing miniature fluorescent tubes are set inside the handrails to direct light on to the deck. The lighting is supplied by cables located in ducts below the deck.